如何在 Django 中注释单个对象而不是 QuerySet？

Question

When annotating something to a model in Django one would write something like this:

Post.objects.all().annotate(total_yes_votes=Count('vote', filter=Q(vote__vote_choice='yes')))

What if I want to annotate on a single object and not all() the objects:

Post.objects.get(id=id).annotate(total_yes_votes=Count('vote', filter=Q(vote__vote_choice='yes')))

By the way, it doesn't work.

Isn't it more efficient to annotate a single object rather than all()?

Answer 1

将调用.get()移到注释之后

Post.objects.annotate(total_yes_votes=Count('vote', filter=Q(vote__vote_choice='yes'))).get(id=id)